Flotation apparatus



Oct. 30, 1 51 w. A. WASLEY ET AL FLOTATION APPARATUS Filed Oct. 4, 1947 Patented Oct. 30, 1951 FLOTATION APPARATUS William Arthur Wesley, Cananea, Mexico, and

John Clement Maclntosh, Bisbee, Aria, assign- V ors to The Cananea Consolidated Copper Company, S. A., a Mexican corporation Application October 4, 1947, Serial No. 778,006 I 2 Claims. 1

This invention relates to flotation apparatus, and is particularly concerned with the provision of improvements in flotation machines having submergedflir pumps. p i lly machines of the The principal feature of the 6 contai five or six ceus) Fagergren type. present invention is the provision, in such ap- 2 The chamber is divided by a series of transverse partitions 5 into a plurality of individual cells q-(only two cells are shown in the drawing, but

paratus, of baflies of improved design which are arranged so as not to impede, the-flow of an ore pulp through the machine, but which minimiz pump. We have found that the provision of such bailles leads to a decided improyement in the recovery of mineral values in the flotation cone centrate produced in Fagergren type flotationlj, machines.

ordinarily the chamber 1 will be long enough to A feed box 6 is provided at one end of the trough' like chamber I. The end wall I of the chamber which separates the feed box 6 from the chamber itself is formed with an opening 8 rotary motion of the pulp' induced by the air 10 A typical flotation machine of the type'to which the invention relates comprises a long,

trough-like chamber divided by transverse par titions into a plurality of cells. The partitions are formed with openings which permit an ore pulp to flow lengthwise from cell to cell through 1 the chamber. An impeller mounted on a ver--.

near its bottom, so that an aqueous ore pulp introduced into the feed box may enter and flow lengthwise throughthe chamber. Openings 9 in the transverse partitions 5 enable the ore pulp 1 jto flow lengthwise from the feed box serially through the several cells to a tailing discharge box I!) at the opposite, end of the chamber.

; A vertical impeller shaft H is mounted substantially centrally in each cell, in bearings l2 tical shaft for rotation in a substantially horizontal plane beneath the normal level of the pulp,

is provided in each cell for introducing air into the pulp. The impeller and shaft are usually enclosed by a housing that extends upwardly from about the impeller to above the zone in which the flotation froth collects. to prevent recirculation of the froth by the impeller.

In apparatus of this character, the invention provides the improvement comprising a pair of thin vertical bafiies positioned below the normal pulp level in each cell. The baiiies extend lengthwise of the trough chamber, parallel to the line of pulp flow therethrough; they are arranged on opposite sides of the impeller housing, and ad vantageously are secured thereto. Except for these baiiles, none are provided in apparatus according to the invention, so that each cell is subsupported on vertical and horizontal frame memtion (clockwise, as indicated by the arrow, in the apparatus shown in the drawings). The impeller also comprises a squirrel cage of vertical bars 20 which rotate with the blades IS. The impeller and impeller shaft are surrounded by a cylindrical housing 2|, the upper portion 22 of which, above the impeller. is of solid wall construction, and the lower portion of which, immediately about the impeller, comprises a cage of stationary vertical bars 20'.

Inside the solid wall upper portion 22 of the housing is, a splash cone 23, which terminates in a substantially cylindrical lower portion 24 located about at the normal pulp level. A series of vanes 25 on a. collar 26 extend laterally from the impeller shaft inside the lower cylindrical portion 24 of the splash cone, and also at about chine equipped in accordance with the invention.

The flotation machine comprises a long troughlike chamber I having a flat bottom Land side walls each having a lower portion 3 which slopes outwardly and upwardlyfrom the bottom and an the normal level of the pulp in the cell. These laterally extending vanes are pitched at an angle to the vertical, thereby forming an air screw which assists in forcing air downwardly when the impeller shaft is rotated in its normal operating direction. The vanes 26 also prevent any accumulation of ore pulp mud in the splash upper portion 4 which is substantially vertical.

cone. The air screw formed by thesejvanes'j is not a part of heretofore known Fagergren type I of the flotation froth bubbles. 1 provide substantial resistance to rotary motion 1 of the pulp induced by rotation of the impeller, thereby minimizing turbulence in the pulp.

In the operation of apparatus as thus far described, an ore pulp to which suitable flotation 1 reagents have been added is introduced into the feed box 8 and flows lengthwise through the chamber I from cell to cell. The impeller shafts are rotated at a fairly high' speed by the motor 15, so that the impeller blades l9, assisted by the air screw vanes 25, suck air downwardly about the impeller shaft through the splash cone 23,

Q and deliver it radially outwardly through the 3 squirrel cage bars 20 and the housing bars 20 1 into the body of the pulp. The air bubbles form a froth in the pulp which rises to the surface while at the same time the depth of the top edge of the baffles below the normal level of the pulp is made maximum at all points. In consequence, the baiiles have a minimum eflect in preventing the froth, as it rises to the surface of the pulp, from flowing laterally to the side edges of-the cell and overflowing into the collecting launders L.

The substantially improved results obtained with Fagergren type flotation machines equipped in accordance with the invention isshown in the following table. One of -flve rows of Fagergren carrying the mineral values of the ore with it and overflows into collecting launders L arranged I alongside the upper edges of the vertical side members 4. The gangue component of the ore does not float, but flows with the main body of the pulp to the tailing discharge box It, through which it is withdrawn.

It is desirable and important that once air has been admitted to the pulp, it be agitated as little as possible, for otherwise many of the froth bubbles will be broken and the mineral values carried thereby will sink. The lengthwise flow of 1 pulp through the apparatus is sufllciently slow a so as not to produce excessive agitation. The rapid rotation of the impeller, however, tends toimpart a vigorous rotary or swirling motion to the pulp. To a considerable extent this is over- 1 come by the cage bars of the impeller housing, but it is not by any means entirely overcome 1 thereby. It is, however, very largely overcome in accordance with the invention by the provision of a pair of substantially vertical thin sheet j ballles 21. These baffles extend radially out from a the impeller housing 2|, on opposite sides thereof, a in a vertical plane parallel to the flow of pulp 1 lengthwise through the apparatus from cell to cell. 3 allel and spaced quite closely to the floor 2 of The bottom edges 28 of the baflles are parthe flotation chamber l. The upper edges 29 of a the baffles slope downwardly from the side 30 adjacent the impeller housing to the side 3| remote therefrom. Thus the width (vertical height) of the bafiles is greatest near the impeller,

1 and progressively less at progressively greater distances outwardly therefrom. The baiiles are stiflened against lateral deflection by straps 32 With the baflles 21 arranged in a vertical plane and parallel to the line of pulp flow through no appreciable resistance to the flow of pulp through the cell, and they cause no deflection in the direction of pulp flow lengthwise through the apparatus which might contribute to breaking Rotary motion which the impeller tends to induce I each cell, as shown and described, they impose However, they do in the pulp is greatest near the impeller and progressively less as the radial distance therefrom increases. the impeller andslope to substantially less width Since the bailles are widest near in the radial direction outwards from the impeller type flotation machines in aconcentrator plant treating sulphidic copper ore was equipped with baiiles 21 and air screw vanes 25 of the character herein described, while the remaining rows were not so equipped. The second column of the table shows the percentage of copper in the tailings withdrawn from the machines in rows 1 to 4 (the rows in which standard Fagergren machines were not equipped with baii'les or air screws), and the third column shows the corresponding analysis of tailings from row 5 (the row of machines that were equipped with baflies and air screws). The data are given for the twenty-two successive days that formed the test period. The difference between the amount of copper present in the tailings from machines in rows 1 to 4 and in the tailings from the machines in row 5 are given in the fourth column of the table.

Table I Row #5 Diff erence, Days g g i' Per Cent Per Cent Copper Copper Copper 1st day 123 098 030 2nd day.- 139 099 040 3rd day 117 .078 039 4th day.. .128 091 .037 5th day-.. 093 032 6th day." Mill Down 7th day .134 090 044 8th day. .117 .080 .037 9th day-- .118 090 028 10th day-. 121 090 .031 llth day .142 111 031 12th day".-- 170 144 026 13th day... .174 .147 027 14th day. .171 152 019 15th day..- 164 144 020 16th day. 176 153 023 17th day 158 141 017 18th day 171 149 022 19th day. 183 169 .014 20th day .192 182 010 21st day .123 012 22nd day 148 012 Averages 148 .122 026 It is evident from the foregoing table that the invention enables a substantial improvement to be achieved in the recovery of copper in the concentrate, as indicated by the markedly and consistently less amount of copper present in the tailings from machines equipped in accordance with the invention, as compared with the tailings from machines not so equipped but operating concurrently as the same ore pulp.

We claim:

1. In flotation apparatus comprising a long trough-like chamber divided by transverse partitions into a plurality of cells, said partitions being formed with openings adjacent the floor of the cells for permitting an ore pulp to flow lengthwise directly from cell to cell through the chamber. an impeller of substantial height rotating in-each cell for introducing air into the pulp therein, said impellers being located substantially in the horizontal planeof the partition openings, and a housing surrounding each impeller, the improvement comprising a pair of thin vertical baflles positioned below the normal pulp level in each cell and substantially in the horizontal plane of the impeller therein, said baflles extending lengthwise of the trough a substantial distance and parallel to the line of pulp flow therethrough from cell to cell and being arranged on opposite sides of the impeller housing, the height of each bafile at the housing being substantially equal to the vertical dimension of the impeller, each cell being substantially free of any obstruction apart from the impeller housing to the flow of pulp lengthwise therethrough, but said baiiles serving to substantially preclude rotary flow of the pulp in the cells.

2. In flotation apparatus comprising a long trough-like chamber divided by transverse partitions into a plurality of cells, said partitions being formed with openings adjacent the floor of the, cells for permitting -an,;..ore.- pulp to flowlengthwise directly from cell to'cell through the chamber, an impeller of substantial height rotating ineach cellifor introducing air into the pulp therein, said impellers being located substantially'in the horizontal pla'ne'of the parti- Q tion openings, and a housing surrounding each impeller, the improvement comprising a. pairof thin vertical baflles mountedv on opposite sides of each impeller'housing below the normal level of the pulp and substantially in the horizontal plane of the impeller,- said bailies alsobeing positioned in a vertical plane parallel to the line 01 flow of the pulp from cell to cell and extending a substantial distance lengthwise of the cell, the bottom edges of said bames being close to and substantially parallel with the floor of the chamber and the top edges thereof being sloped downwardly from the side thereof adjacent the impeller housing to the side remote from said housing, the height of the baflles thus being greatest near the impeller, and there being substantially equal to the height of the impeller, and progressively less at progressively greater distances outwardly from the impeller, each cell being substantially free of any obstruction apart from the impeller housing to the flow of pulp lengthwise therethrough, but said baifies serving to substantially preclude rotary flow of the pulp in the cells.

WILLIAM ARTHUR WASLEY. JOHN CLEMENT MACINTOSH.

REFERENCES CITED The following references are ofgrecord file of this patent:

Number Name -5 1,984,366 Fahrenwald pea-i8, 1934 2,073,148 Gayford -Mar.;,9, 1'931 2,304,270 Mead Dec 8,1942

OTHER REFERENCES;

Handbook of Mineral Dressing, Tagg'f" section 12, pages -66, 67, and 68. v

The Laboratory Fagergren Flotation I chine, American Cyanamid Company,

teller Plaza, New York, N. Y. 

